This invention broadly relates to an improved lamination method, the product produced thereby, and the apparatus used in carrying out the method. More specifically, the invention relates to a method for preparing a heat sealed laminated product of at least three plies.
The state of the art is indicated by the following references which are cited here for the record: U.S. Pat. Nos. 3,360,412 issued to James, 3,562,000 issued to Williams, 3,081,214, issued to Strome, 3,018,189 issued to Traver, 2,920,733 issued to Sorel, 2,897,109 issued to Voigtman, 2,922,883 issued to Giaimo; and also the following U.S. Pat. Nos. 2,154,493; 2,154,474; 2,334,485; 2,423,869; 2,637,673; 2,650,213; 2,702,580; 2,174,569; 2,714,571; 2,723,935; 2,728,703; 3,276,900; 2,890,590; 3,287,197; 2,794,485; 3,149,013; 3,196,766; 2,867,560; 2,922,732; 2,940,869; 2,988,051; 3,057,766; 3,093,525; 3,132,065; 3,157,526; 3,247,041; 3,256,598; 3,034,974; 2,861,022; 2,715,075; 3,308,509; 3,298,559; 3,256,560; 2,259,347; 2,538,520; 2,551,591; 2,769,206; 2,820,722; 3,062,698; 3,457,139; and 3,539,428.
While the invention subject matter disclosed in said copending application Ser. No. 62,295 and Williams U.S. Pat. No. 3,526,000, are both highly useful and practical, the present inventive disclosure deals with the discovery of an improvement which has been found relative to the invention disclosed by Williams. In the Williams U.S. Pat. No. 3,526,000 method, it may in some instances be difficult to operate with an extruded film forming plastic material having a very thin thickness because the heat capable of being carried thereby is limited. Accordingly, the present invention deals with an improved species of operation (relative to the generic broad disclosure of the Williams method) which finds application for use with very thin layers of extruded film forming plastic material.
One object of this invention is to provide an improved lamination method and an improved product produced thereby.
Another object of the present invvention is to provide an improved method of preparing a laminated product comprised of at least three and preferably four or more laminated layers.
Still another object of the present invention is to provide an improved method wherein a laminated product comprised of three or more layers can be made in general by passing the three or more layers essentially simultaneously between a chill roller and a nip roller and wherein one of the three layers is subjected to a pre-heating step such that the heat imparted by the film forming plastic material and the pre-heating uniquely cooperate to bond together the layers that form the finished product.
Still another object of the present invention is to provide an improved method of preparing products such as a water vapor proof, flexible, heat sealable barrier material type of product.
Still another object of the present invention is to provide an improved lamination method applicable for use with very thin layers of a hot extruded film forming plastic material which constitutes one of the plies of the finished laminated product.
Other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.